Botanical Diversity at Savura, a Lowland Rain Forest Site Along the PABITRA Gateway Transect, Viti Levu, Fiji1
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Botanical Diversity at Savura, a Lowland Rain Forest Site along the PABITRA Gateway Transect, Viti Levu, Fiji1 Gunnar Keppel,2 Jone Cawani Navuso,2 A. Naikatini,4 Nunia T. Thomas,4 Isaac A. Rounds,2,4 Tamara A. Osborne,5 Nemani Batinamu,3 and Eliki Senivasa3 Abstract: Savura is one of the seven focal sites of the Pacific-Asia Biodiversity Transect (PABITRA) Gateway Transect in Fiji. The site is composed of tropical lowland rain forest located in southeastern Viti Levu and consists of two adja- cent watershed reserves, the Savura Forest Reserve and the Vago Forest Re- serve. A total of 560 indigenous species (52% endemic) of vascular plants is recorded for this focal site. Savura has been chosen for the establishment of a large permanent plot of 12 ha following the methods proposed by the Centre of Tropical Forest Science (CTFS). This involves the recording of name, diam- eter at breast height (DBH), and precise location of every tree with 1 cm or more DBH. A total of 5,494 individuals with a total basal area of 2,752 m2 was recorded in the first 6,000 m2 of this CTFS/PABITRA permanent plot. The Myristicaceae (species of the genus Myristica) was the dominant family in num- bers of individuals (14.4%) and basal area (35.6%). Tree ferns (Cyatheaceae [8.2% of individuals, 14.6% basal area]) and the Clusiaceae (8.6% of individuals, 12.8% basal area) are other major components. After this initial census, sub- sequent censuses will be carried out every 5 yr and should give insights on spa- tial dynamics, recruitment and mortality, and long-term changes in populations of tree species. Savura, one of the seven focal sites of the comprises 24.7 ha of lowland rain forest; Fiji Pacific-Asia Biodiversity Transect (PABI- the Savura Forest Reserve was established in TRA) wet-zone transect (Keppel 2005, this 1963 and comprises 396.5 ha. No trees have issue), is located in the province of Naitasiri been removed from either reserve since their and includes two adjacent forest reserves, establishment, but before that, traditional Vago and Savura, that are catchment areas logging, the occasional removal of large trees for Savura Creek, which provides much of for house construction, is likely to have oc- Suva’s water supply (Figure 1). The Vago curred at least in parts of the reserves. Forest Reserve was established in 1959 and Because of its comparative accessibility and its protected status, Savura and the sur- rounding areas have been subject to previous 1 The Savura 12-ha Permanent Plot is funded by the botanical collections and ecological studies University Research Committee (URC) of the University of the South Pacific, Suva, Fiji. Manuscript accepted 23 investigating the demography of Balaka mi- April 2004. crocarpa Burret (Ash 1988) and Cyathea hornei 2 Biology Department, School of Pure and Applied Baker (Copel.) (Ash 1987). Despite this, no Sciences, University of the South Pacific, Suva, Fiji. species list for the area exists. In this paper 3 Forestry Department, Ministry of Fisheries and we provide a preliminary list of species by Forests, Suva, Fiji. 4 South Pacific Regional Herbarium, Institute of Ap- incorporating data from collections at the plied Sciences, University of the South Pacific, Suva, Fiji. South Pacific Regional Herbarium and from 5 Geography Department, University of the South specimens listed in Smith (1979, 1981, 1985, Pacific, Suva, Fiji. 1988, 1991, 1996) and in Brownlie (1977). Also included are species recorded from an Pacific Science (2005), vol. 59, no. 2:175–191 altitudinal transect on adjacent Mt. Korobaba : 2005 by University of Hawai‘i Press (Hassal and Kirkpatrick 1985, Kirkpatrick All rights reserved and Hassal 1985), which is similar in altitude 175 176 PACIFIC SCIENCE . April 2005 Figure 1. Map showing the boundary of the Vago Forest Reserve and location of the study site for the 12-ha perma- nent plot (indicated by arrow). The map also shows Savura Creek and Wailoku Creek, which are part of the Savura Forest Reserve and the Wailoku Forest Reserve, respectively. Inset is the climate diagram for Nausori Airport, located 14 km east of Savura. to Mt. Nakobalevu in the Savura focal site tree that is 1 cm or more in diameter. The (see Figure 1). project is a joint effort between the University Currently, a 12-ha permanent plot is being of the South Pacific and the Fiji Forestry De- created in the Vago Forest Reserve following partment. After completion of the initial cen- Centre for Tropical Forest Science (CTFS) sus, which is anticipated by early 2005, the protocol (Condit 1998), which involves map- plot will be revisited every 5 yr. In this paper ping, measuring, and identification of every we present a preliminary species list, profile Botanical Diversity at Savura in the Fiji PABITRA Gateway Transect . Keppel et al. 177 diagrams, and initial preliminary results of were used to assess whether a species is en- the first 6,000 m2 of this CTFS/PABITRA demic, indigenous, or introduced. permanent plot. Profile Diagrams materials and methods Profile diagrams were constructed by placing two 60 by 6 m transects into homogeneous Study Area vegetation types. One was placed on a slope The Savura focal site is located in southeast- and the other on a plain. Within each of these ern Viti Levu, about 8 km north of Suva. It transects every tree of 10 cm or more in di- is mostly covered by lowland rain forest. The ameter at breast height (DBH) was identified climate diagram of Nausori (Suva) Airport and approximately mapped. For each such (Figure 1 inset), located 14 km east of the fo- tree DBH was measured and the bole height, cal site, shows a mean annual rainfall of 2,926 crown height, and crown width estimated. mm and a perhumidity index (Walsh 1992) of These data were then used to draw a profile 20. Nausori Airport is located on the flood- diagram. plain of Fiji’s largest river, the Rewa, there- fore the focal site is likely to receive more Tree Census rainfall due to additional orographic rainfall. 2 The climate may be best described as tropical Within the 6,000 m every tree with a DBH wet to superwet (Richards 1996). Topogra- of 1 cm or more was measured, tagged, iden- phy is very uneven with steep slopes and tified, and mapped following Condit (1998). ridges. Landslides are common. However, instead of aluminum tags, nylon To begin the study and to provide some ribbons (with numbers written using white species identification the first hectare of the correction fluid) were used for this initial cen- permanent plot (which is intended to be 12 sus. Tree identifications were made by J.C.N. ha in size) has been set up in the Vago Re- and G.K. using parataxonomy (vernacular serve (see Figure 1). Data collection for this names). This involves identification of trees study was restricted to the first 6,000 m2 of based on characteristics of the bark and other the initial 1-ha plot. Because of the dense vegetative features and allows identification of canopy, global positioning system (GPS) plants to the family, genus, or species level, readings are difficult to obtain in the forest. depending on the plant. Scientific identifica- However, GPS coordinates obtained near tion of the various species is currently under the bottom of the nearby Vago Waterfall in way. In addition, Neil White (Biology De- the same reserve were 18 0 04.83300 S and partment, University of the South Pacific) 178 0 26.50500 E (D. Boseto, pers. comm.). has created an MS Access database following the format suggested by Condit (1998) and data entry will commence once identifications Preliminary Species List to the species level are completed. A species list of plants likely to be encoun- tered was constructed by listing all species results reported from Savura, Vago, Wailoku, Colo- Species i-Suva, Mt. Nakobalevu, and Mt. Korobaba (see Figure 1 for locations). These records A total of 560 indigenous species (52% en- were obtained from Flora Vitiensis Nova demic) was recorded (see Appendix 1). Of (Smith 1979, 1981, 1985, 1988, 1991, 1996), these, 345 (71% endemic) were dicotyledons, the database of the South Pacific Regional 117 (28% endemic) were ferns, 93 (14% en- Herbarium, and a previous study on Mt. demic) were monocotyledons, and 5 (none Korobaba (Kirkpatrick and Hassal 1985). endemic) were gymnosperms; 55 of the 93 Planted ornamentals were ignored. Smith’s monocotyledonous species were orchids. In volumes (1979, 1981, 1985, 1988, 1991, 1996) addition 27 introduced species were recorded. 178 PACIFIC SCIENCE . April 2005 Figure 2. Forest profile diagram of lowland rain forest on a plain in Savura, Naitasiri Province, Fiji. Symbols of trees over 10 cm DBH: Albo, Alpinia boia; Alsp, Alstonis sp.; Anac, Buchanania sp.; Baed, Barringtonia edulis; Casp, Canarium sp.; Cavi, Calophyllum vitiense; Cyin, Cyathocalyx insularis; Dibi, Dillenia biflora; Elsp, Elaeocarpus sp.; Enma, Endosper- mum macrophyllum; Ensp, Endiandra sp.; Exsp, Excoecaria sp.?; Fism, Ficus smithii; Gamy, Garcinia myrtiflora; Gice, Gi- ronniera celtidifolia; Gopu, Gonystylus punctatus; Hafl, Haplolobus floribundus; Heor, Heritiera ornithocephala; Mysp, Myristica sp.; Nesp, Neuburgia sp.; Path, Pagiantha thurstonii; Plsp, Plerandra sp.; Xy, Xylopia sp. Profile Diagrams error using the parataxonomic method be known. The profile diagrams (Figures 2 and 3) show Species of Myristica (Myristicaceae) are that species of dominate the canopy Myristica dominant in the area surveyed. They account and subcanopy with emergents of Endosper- for 14.4% of individuals (Table 1) and for on plains, and mum macrophyllum Calophyllum 35.6% of the basal area (Table 2). The Clu- vitiense, Gonystylus punctatus, and species of siaceae (species of Calophyllum and Garcinia) Syzygium dominate the canopy and sub- and tree ferns (species of Cyathea [Cyathea- canopy on slopes.